1. Field of Invention
The present invention relates to a chip on film structure. More particularly, the present invention relates to a chip on film structure for a liquid crystal display.
2. Description of Related Art
Recently, liquid crystal displays (LCD) have been widely applied in electrical products, due to the rapid progress of optical technology and semiconductor technology. Moreover, with the advantages of high image quality, compact size, light weight, low driving voltage, and low power consumption, LCDs have been introduced into portable computers, personal digital assistants, color televisions, and are gradually replacing the cathode ray tubes (CRT) used in conventional displays. LCDs have become the mainstream display apparatus.
Conventional display panels have two types of tape carrier packages (TCPs). Each TCP type contains only data driver chips or scan driver chips, which are respectively connected to the data lines or the scan lines to drive the pixels of the display panel. Display panel demand and cost concerns have created a tendency to omit the additional tape carrier packages, for example, by directly bonding driver chips on the glass substrate (COG) or bonding driver chips on the film substrate (COF).
The chip on film technique may simplify the manufacturing process, save the prime cost, reduce the package volume, and the product made by the COF technique may become popular. However, input pads and the output pads of the chip on film structure packaged with the driver chip may be cut when the chip on film structure is punched from the tape, and the metal particles may be generated. The metal particles generated from the punching process may be dispersed onto the chip circuit and the metal particles may then short circuit the circuit on the chip on film structure, thus the reliability of the chip on film structure is reduced.
U.S. Pat. No. 6,495,768 has disclosed a tape carrier package (TCP) structure. The input pads of the TCP structure are arranged inner than the cutting edge of the film substrate, and the extending portions of the output pads extending through the cutting edge may have a thinner width. However, the output pads in the prior art would further have a testing area disposed outer the cutting edge, thus the arrangement and the prime cost of the chip on film structure have become a consideration.